HILO, Hawaii  The state has allocated $4.9 million to fight invasive species including coqui frogs, the amphibian accused of threatening Hawaii's fragile ecosystem and disrupting the sleep of island residents.

The funding sets aside more than $2.9 million to hire 58 additional inspectors at Hawaii's airports and harbors to help spot nonnative species before they enter the islands. The funds will boost the state's inspection staff by more than 75 percent.

Lawmakers allocated another $2 million for ongoing efforts to kill the frogs with citric acid and hydrate lime. Most of those funds will go to the Big Island, where coqui numbers are greatest.

Experts believe the first coqui frog -- or frogs -- hitched a ride to Hawaii in a plant shipped from Puerto Rico or Florida.

Hawaii's year-round temperate weather and open space have given the frogs an ideal place to reproduce. A lack of natural predators has prevented anything from keeping their numbers in check.

While beloved in their native Puerto Rico, the frogs have become a major nuisance in Hawaii, where coqui population densities exceed anything seen in their Caribbean homeland.

On the Big Island and Maui, where the infestations are most serious, local residents say the experience of listening to thousands of chirping frogs rivals that of hearing jet planes constantly taking off at an airport.

Officials also worry the coqui could threaten Hawaii's many endangered bird species by eating the bugs the birds rely on for food.

The Big Island will receive $1.8 million to treat some 5,000 acres that have become infested with coqui.

Maui, the site of the next biggest outbreak, will get $150,000 to treat 150 acres. Oahu and Kauai will each get $50,000 to treat 15 acres on their respective islands.

Chemicals mixtures of citric acid or hydrated lime used to eradicate the coqui only kill 80 percent of the coqui in heavily infested areas, and survivors can return to former densities in as little as two months.

Officials are looking for other ways to control the frogs. A team of researchers will head to Puerto Rico in August to look for parasites they might be able to bring to Hawaii, said Kyle Onuma of the state Department of Agriculture.

Releasing sterile males to break the reproduction cycle is another possible way to control the frogs, said University of Hawaii-Hilo biologist Bill Mautz.

"In the long term, biological control is the solution," said Billy Kenoi, the anti-coqui coordinator for Big Island Mayor Harry Kim.